Chromosomes of Brants' whistling rat and genome conservation in the Otomyinae revealed by G-banding and fluorescence in situ hybridization.
Conventional G- and C-banding were used to describe the chromosomes of the whistling rat, Parotomys brantsii. This species has a diploid number of 42 chromosomes. C-banding showed that large blocks of pericentromeric heterochromatin or entirely heterochromatic short arms characterize most chromosomes. G-banding and fluorescence in situ hybridization (FISH) incorporating two laboratory mouse chromosome paints were used to compare the genomes of P. brantsii, the bush karoo rat (Otomys unisulcatus; 2n = 28), and the vlei rat (O. irroratus; 2n = 28-31). The FISH results showed that sequences corresponding to mouse chromosome 2 are conserved as a single chromosome in O. irroratus but are found on two separate chromosomes in P. brantsii and O. unisulcatus. In contrast, a mouse chromosome 6 paint showed hybridization to single chromosomes in all three species examined. When taken together, the FISH and cytogenetic results produce two important findings: (1) previously undetected homoeologies between the two Otomys species can be identified and (2) a high proportion of conserved chromosomes exists between P. brantsii and O. unisulcatus. This, in conjunction with previously reported allozyme and immunoblot data, raises serious questions about the validity of the current generic taxonomy of the Otomyinae.
Rambau
R V
RV
Department of Zoology and Entomology, University of Pretoria, South Africa.
Harrison
W R
WR
Elder
F F
FF
Robinson
T J
TJ
D000818:Animals; D000835:Animals, Wild / Q000235:genetics*; D002871:Chromosome Banding; D002874:Chromosome Mapping; D005260:Female; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D051379:Mice; D051381:Rats / Q000235:genetics*; D013045:Species Specificity